Mercury relay



A"8-. 1930, A. s. FITZ GERALD 1,773,036

MERCURY RELAY Filed Jan. 12, 1928 2 Sheets-Sheet l Iwventov; Adan S.Fitz Gercdd; by Wad/wa His Attovneq Aug. 12, 1930. A. s. FITZ GERALD1,773,036

' MERCURY RELAY Filed Jan. 12, 1928 2 sheets-sh et 2 Q/JZ 5 I 37 I 40 oW M 5 2% 5 Z 2/ J 3? 9 Li;

- Inventor:

Alorn S. Fitz Gerald,

His Attorney.

' such switches arenot suitable for'controllmg Patented Aug. 12, 1930UNITED mm PATENT OFFICE ALAN S. FITZGERALD, OF SCHENECTADY, NEW YORK,ASSIGNOB TO GENERAL ELEC- i TRIO COMPANY, A CORPORATION 01' NEW YORKlanolin! RELAY Application filed January 12, 1928 Serial No. 248,317.

My invention relates to circuit controller to liquid contactcontrollers, such as sealed mercury contact switches, are well known inthe art.. By the use of these controllers in,

circuits which must be opened or closed frequently, the burning ofcontacts and consequent maintenance which is an incident to the use ofmetallic contacts may be avoided, and the life of the controllerincreased.

In the mercury contact switch heretofore though any other suitablematerialv which in general use, the mercury and contacts have beenenclosed within a sealed tube pivoted to permit a limited rockingmotion. While this arrangement has been more or less satisfactory wherethe current carrying capacity of the switch was small, and the operatingforces available to tilt the tube were ample,

large currents because of the difliculty of providing connectionssufficiently flexible to avoid hindering the operations of the mercurytube while at the same time havin suitable current carrying capacity andsu' cient strength to withstand ordinary handling.

It is an object of my invention to overcome the abovementioneddifiiculties by substituting for the pivoted mercury tube, a stationaryvessel and causing the mercury therein to be diplaced byelectro-magnetic influence to close the contacts.

Another object of the invention is to pro vide a liquid contact electricswitch of a relatively large current carrying capacity.

which may be operated with a comparati ly small amount '0 power. A

The preferred embodiments ofmy invention, as illustrated intheaccompanying drawi'n will now be described, and the features .w 'ch I'believe to be. new -.and-patentable will be pointed out in-the appendedgram ofthe preferred embodiment of my in vention in a mercury contactswitch. I Fig. 2

1 is a cross-sectional view of the electromagnet shown in Fig. 1', takenon the line 2-2. Fig.

3 shows a modification of my invention in which the electromagnet isreplaced by a pen manent magnet. Fig.4 illustrates an applicationof thesame principle with the interposition ofmecnanical means between themercury chamber and the switch which is illustrated as a disconnectingswitch of a well known type, though it is obvious that it might beapplied to any other t pe of switch.

Referring now to Fig. 1 of t e drawing, I

have illustrated a mercury contact switch comprising a vessel1,containing the main switch contacts 3 and 3. This vessel is preferablyof glass and hermetically sealed, ali may be readily formed in thedesired shape may be used. It is not necessary to the op-' eration ofthis device that the vessel be sealed,

although in practice, it is usuall desirable. The contacts 3 and 3" arealso sea ed into the vessel in case a sealed vessel is used, and theymust be insulated from the vessel if it is made of electricallyconductive material.

This vessel comprises a main mercury cham' and 11, sealed into thevessel. This mercury chamber 4 is filled with mercury which rises in thetubes 6 and 7 to a level 12 substantially below the contacts 3 and 3*.Contacts 3 and '3 might be placed normally below the mercury levelifintended to be normally closed. Surrounding the mercury chamber 4'. inthe position in which the electrodes 8 and 9 .are mounted is a C-shapedelectromagnet-13 having'a winding 14 terminating in the loads 15 and16'. That is, the portion of the mercury chamber containing theelectrodes 8 and 9 is arranged in the air gap of the electrom agv net13, which ispreferably made only long enough to receive the vessel sothat a maxi mum flux ma be obtained for a given magneto-motive orce.

Current of low voltage but high amperage is supplied to the electrodes 8and 9, through binding posts 10 and 11 mounted in the main mercurychamber e from the secondary wind The urimar 17 of a m .rner 1senerglzed winding 1% of the winding 19 O1 in series with e excitingelectromagnet 1 By this means the current flowing between the electrodes8 and 9 1S kept substantially phase with the flui: set up by theelectromagnet l3. lhe primary of the transformer 18 and the winding 14are enerized through the leads 20 and 21 from a suit able source ofalternating current 22. In this circuit may be placed a suitable switch28 i the electrodes 8 and 9 through the mercury as a conductor. Thismercury which is carrying the greater part of the current is in the airgap of the electromagnet13 and is acted upon in the same manner as thearmature conductors of an electric motor. This elec- 'tromagnctic forcepropels the mercury to the right, and the mercury rises in the contactchamber 5 to the level 24 and falls in'the tube to the left until thedifference in hydrostatic head just balances the propulsive force actingon the mercury. 1

As the mercury rises in the chamber 5, the circuit is completed betweenthe main contests 3 and 3 This circuit will be maintained closed as longas the switch 23 is closed to energize the transformer 18 and excitingvinding 14, but will be opened as soon as they are deenergized.

.In Fig. 3, I have represented a further modification of my inventionwhere the magnet 13 is 21;. ordinary permanent magnet and the electrodes8 and 9 are connectedto a direct current source through a reversingswitch 39. This modification may be used where the change in level ofthe mercury is small. Fig. 4 illustrates an application of the samerinciple involved in the apparatusjust decribed to the operation of adisconnecting witch or to operate any other movable device. In thisfigure the disconnecting switch comprises a base 26 on which are mountedthe split contact 27 and the split finger 28 in which is pivoted thedisconnect blade 29.

The disconnect blade has a projecting arm 30 to which is pivoted theoperating link 31. The operation of the switch is similar in prin cipleto that described in connection with Fi 1, with. the exception that thedifference in head of the two columns of mercury in the which theoperation of this 37 and 38 is im )ressed upon a piston 3a perating in acylin er 33. The piston 34 is e nnected by means of a link 82 to theoperating lin 31. In addition, a double pole double row switch 39 isprovided in the circuit of the exciting winding for reversing thecurrent therein. This reversing of current in the exciting winding 14:relative to that between the electrodes causes a reversal in the direction of displacement of the mercury, which, in turn, may be utilized toopen and close the disconnecting switch 29. A switch 40 is provided inthe supply leads 20 and 21 to control. the operation of thedisconnecting switch. The switch 40 is shown as a manually open ateddevice, though obviously it may consist contacts of some relay or othercontrol device. here desired the switch 40 may, be omitted and-theswitch controlled entirely by the switch 39.

While I have shown and described only the preferred embodiments of myinvention, it is not limited to the structure disclosed but ohviouslyincludes other modifications such as the use of a single electromagnetwith a shed ing coil such as is well known in the art as applied to theinduction disc relay, in place of the electroma netic means illustrated;or in place of a sealed vessel, an open vessel of proper form might beused; or in place of the-glass, vessel with sealed electrodes a metallievessel might be used with the contacts 3 and 3 properly insulated.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:-

1. In combination, an electromagnet, a

transformer having a primary winding connected in series with saidelectromagnet, and a secondary winding; a vessel arranged in the air gapof said clectromagnet containing spaced contacts, an electricallyconductive liquid, and electrodes connected to the sec; ondary windingof said transformer for supplying an electric current to said liquid;and asource of alternating current for energizing said electromagnet inseries with said transformer whereby said liquid is displaced from itsnormal position to control a circuit be tween said-contacts.

I 2. In combination, an electromagnet, a transformer having a. primarywinding connected'in series with said electromagnet, and a secondarywinding, a vessel arranged in the air gap of said electromagnet,containing an electrically conductive liquid and electrodes connected tothe secondary winding of said transformer for supplying an electriccurrent to said liquid, and a source of alternating current forenergizing said electromagnet in series with said transformer wherebysaid liquid is actuated.

In witness whereof, I have hereunto set my hand. this 11th day ofJanuary, 1927.

ALAN S. FITZGERALD.

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